Unit 1 Flashcards
(136 cards)
1
Q
What is made when an alkaline metal is used to neutralise an acid
A
Salt and hydrogen
2
Q
What is made when a metal carbonate is used to neutralise an acid
A
A salt , water and carbon dioxide
3
Q
What is made when a metal oxide is used to neutralise an acid
A
Salt and water
4
Q
What is made when a metal hydroxide is used to neutralise an acid
A
Salt and water
5
Q
Name a method used to follow the rate of a reaction
A
Collecting gas over water
6
Q
When does a reaction stop
A
When one of the reactants is used up
7
Q
What is a limiting factor
A
The reactant that is in the shortest supply
8
Q
What are the important factors associated with collision
A
Reactant particles have to collide
They must have sufficient energy to overcome the activation energy
Reactant particles must have the correct geometry
9
Q
How do you recognise a concentration experiment
A
It will say H2O2 and/or KI
10
Q
What is the aim of a concentration experiment
A
To determine the effects of changing KI concentration has on reaction rate
11
Q
In a concentration experiment why is the potassium iodide solution acidified?
A
To supply h+ (aq) ions
12
Q
What is the indicator used in the concentration experiment?
A
Starch solution
13
Q
What is ommited from the concentration experiment equation
A
K+(aq) i.e spectator ions
14
Q
What was timed in the concentration experiment
A
Start time when H2O2 is added
Stop time when blue black colour appears
15
Q
Why is this a good experiment to measure concentration
A
The colour change from colourless to blue black is instant
16
Q
What does an increase of temperature do to a reaction rate
A
It increases it as it increases the average number of molecules with q kinetic energy equal to or greater than the activation energy
17
Q
How do you calculate the reaction rate
A
Rate=1
-
t
18
Q
How long do explosive reactions take to come to completion
A
Come to completion almost instantly
19
Q
What are photochemical reactions
A
In some chemical reactions light energy is used to increase the number reactant molecules with energy equal to or greater than the activation energy
20
Q
Give an example the photochemical reaction
A
Photosynthesis: light energy is absorbed by chlorophyll to help co2 and h2o combine to make glucose and oxygen
21
Q
What is activation energy
A
The minimum Connecticut energy required to produce a product
22
Q
What is temperature
A
A measure of the average kinetic energy of all the reactant particles
23
Q
On a potential energy diagram Will an exothermic reaction have a negative or a positive and enthalpy change
A
Negative as it gives off heat
24
Q
What are some examples of exothermic reactions
A
Combustion reactions neutralisation reactions
MAZIT metal + Acid
Metal oxide + Acid
Metal carbonate +Acid
Alkali +Acid
Displacement reaction
25
On a potential energy diagram Will an exothermic reaction have a negative or a positive and enthalpy change
Positive as it takes in heat
26
What are some examples of endothermic reactions
Dissolving certain salts (ammonium nitrate)
| ethanolic acid + sodium hydrogen carbonate
27
What do small activation energies indicate
The reaction to take place at room temperature
28
What is an activated complex
As a reaction proceeds from reactants to products an intermediate state is reached at the top of the activation energy barrier at which a highly unstable complex called activation complex is formed
Activated complexes are very unstable and only exist for a very short amount of time
29
What is a catalyst
I cattle speeds up or slows down the rate of a chemical reaction without being used up or change during the reaction
a catalyst works by providing an alternate reaction pathway
This new reaction pathway has a lower activation energy
30
How does using a catalyst Lowering an activation energy speed up reactions
I lowering the activation energy and more of the reacting particles of kinetic energy is equal to or greater than the catalysed activation energy
31
What are the two types of catalyst
Homogeneous hertogeneos
32
What is a homogenous catalyst
Catalysts and the reactants are in the same state of matter
33
What is the hetogeneos catalyst
The catalyst and reactants are in a different state of matter
34
What are the three stages of a catalytic reaction
Adsorption reaction and desorption
35
What happens during adsorption
Reactants for my temporary bond with the catalyst. this weakens the bonds within the molecules thus the activation energy is lowered
36
What happens during reaction
The molecules react on the catalysts surface. the collision geometry is more favourable since one of the molecules is fixed
37
What happens during desorption
The product molecules leave the catalyst and the vacant site to be occupied by another reactant molecule. In other words catalysts can be reused
38
What is catalytic poisoning
Catalytic poisoning occurs when a substance (impurity) forms a strong bond with the active site on the surface of the catalyst so reducing the catalyst efficiency
39
How do you regenerate a poisoned catalyst
It involves cleaning the catalyst by removing impurities from activation site. this can be achieved by heating a catalyst and passing a gas over the catalyst that reacts with the impurities
E.g carbon removed by reacting it with oxygen for carbon dioxide
40
What is the catalyst Vanadium (V) oxide used for
It is used during the process: contact
The reaction is:
2SO2+O2 -----> 2S03
It is important during the manufacture of sulphuric acid
41
What is the catalyst iron used for
It is used during the process: Haber
The reaction is:
N2+3H3 -----> 2NH3
It is important during the manufacture of Ammonia
42
What is the catalyst platinum used for
It is used during the process: catalytic oxidisation of ammonia
The reaction is:
4NH3+5O2+4NO -----> 6H2O
It is important during the manufacture of nitric acid
43
What is the catalyst nickel used for
It is used during the process: Hydrogenation
The reaction is:
Unsaturated oils+H2 -----> saturated fats
It is important during the manufacture of Margerine
44
What is the catalyst aluminium silicate used for
It is used during the process: catalytic cracking
The reaction is:
Breaking down long chain carbon molecules
It is important during the manufacture of fuels and monomers for the plastics industry
45
What is metallic bonding
Metallic bonding occurs between atoms of metals
Metallic bonding is the electrostatic force of attraction between the positive metal core and the negatively charged delocalised electrons
46
What are the seven metallic elements among first 20 elements
Group 1- lithium sodium potassium
Group 2-Beryllium magnesium calcium
Group 3- aluminium
47
What does low electronegativity mean
Things like metals have very little attraction for bonding electrons
48
How can metallic lattice structures conduct electricity
Outer do you localised electrons can move freely through the overlapping energy levels
49
How are most metals, except for the exception of mercury, solids at room temperature
The bonds are relatively strong forces of attraction therefore metals are solid at room temperature
50
What do metals tend to be
Malleable and ductile
51
What type of bonding do metals do
Metallic
52
What two types of bonding do non metals do?
Covalent and monatomic
53
What two types of covalent bonding are there
Molecule and network
54
What are the 3 monatomic elements in group 0
Helium, neon, argon
55
Why are noble gases described as monatomic
They exist as one single gaseous atoms at room temperature
56
How do we know there is a force of attraction between nobel gases
They can form solids and liquids
57
What are the forces of attraction between noble gases known as
London Dispersion Fources of attraction
58
What are discrete molecules
Small groups of non-metal atoms bonded together by strong covalent bonds (intramolecular forces of attraction)
These discreet molecules contain weak London Dispersion forces of attraction between their molecules that dictates their state of matter and physical properties
59
How many discrete molecular elements are their within the first twenty elements
8
60
What are London Dispersion forces of attraction?
Temporary dipole - induced dipole fouces of attraction
| It is these intermolecular fources of attraction that dictates the melting and boiling point of the monatomic elements
61
What are the 8 discrete molecular elements among the first 20 elements?
```
Carbon ( in the form of fullerenes)
Nitrogen (N2)
Phosphorus (P4)
Oxygen (O2)
Sulphur (S8)
Fluorine (F2)
Chlorine (Cl2)
Hydrogen (H2)
```
62
What do the boiling points of halogens and noble gases increase with
Atomic number
molecular mass
increasing London dispersion forces of attraction
63
How many molecular solids are there on the first 20 elements of the periodic table
2
Phosphorus
sulphur
64
What are molecule carbon fullerenes
Discrete covalent molecules. The smallest is spherical in shape, C60
The force of attraction between fullerenes is London Dispersion forces of attraction
65
Name the covalent network elements in the first 20 elements of the period table
Group 3- boron
Group 4- carbon (dimond, graphite)
Silicon
66
Describe boron as a covalent network element
Forma a structure of B12 groups that are inter-bonded with other B12 groups
The resulting element is almost as hard as diamond and is used in the manufacture of pyrex glassware
Able to withstand high temperatures
67
Describe silicon and carbon (diamond) as a covalent network element
These structures have an infinite three dimensional network where each atom is covalently bonded (tetrahedral) to four other atoms
Very hard and rigid
Do not conduct as their elections are held in covalent bonds
High mpt
68
```
Describe carbon (graphite)
as a covalent network element
```
Three covalent bonds from each carbon atom in one plane, forming hexagonal rings, the fourth unpaired electron is delocalised, forming weak bonds between layers
Aka strong bonds without layers but only weak interactions between layers
Graphite conducts through the ability of electrons to flow across layers
69
What are some of the trends in the variations of the physical properties of the elements both across a period and down a group
```
Melting point and boiling points
density
atomic size (or covalent radii)
ionisation energy
electronegativity
```
70
What are the trends in melting and boiling points in group 7 (the halogens) and group 0 (the noble gasses)
Increase with atomic number, molecular mass London Dispersion forces of attraction
71
What are the trends in melting point and boiling points in group 1 (alkali metals)
Melting points decreased down group 1
72
Why do melting points and alkali metals decrease as you go down
Because there are more shells of electrons the electron shells shield the delocalised electrons from the positive nuclear core which results in weaker electrostatic forces of attraction between the positively charged nucleus and the negatively charged do delocalised electrons
73
What are the trends and melting and boiling points across a period
Across a period melting and boiling points increase to maximum near the centre of the period before decreasing towards group zero
74
What is the trend in density across a period
It increases to a maximum towards the centre of the period before decreasing towards group 0
75
What does density increase with down a group
Atomic number
76
What is atomic size
It is the defined as the distance between the nuclei of two covalently bonded elements
77
What can the distance between the nuclei be measured with
X-ray defraction
78
Why is covalent radii period property
There are two discrete bonds
79
Atomic size increases...
Down the group
80
Atomic size decreases...
Across a period...
81
What happens to the nuclear charge across a period
Increases
82
What is first ionisation energy
the energy required to remove one mole of electrons from one mole of atoms in their gaseous state
83
What is the formula for first ionisation energy
E(g)-->E(g)*+e-
84
What type of process is first ionisation
Endothermic process
85
What is the trend in the space between electrons nuclear core when going down to group
To outer electrons are further away from the positive nuclear charge
86
There are increased electron shielding....
Due to added energy levels
87
What does increased electron shielding result in
A decrease in the electrostatic force of attraction between the positive nucleus and negatively charged outer electron
88
What is the trend and First ionisation energy going down the group
It decreases
89
What is second ionisation energy?
The energy required to remove 1 mole of electrons from 1 mole of single positive ions in their gaseous state
90
What is the formula for second ionisation energy
E*(g) --> E2*(g) +e-
91
Why is there such a large increase in ionisation energies from the first ionisation energy to the second ionisation energy in elements in group 1
The first ionisation energy is for the removal of electron in the outer energy level
The second ionisation energy requires removing an electron from the inner stable octet with electrons,
92
Why is it harder to remove electrons from an inner stable octet
They nearer to the positive nucleus and subject to lesser degree of electron shielding therefore a greater electrostatic force of attraction between the positive nucleus and the negative electrons so it requires much more energy to remove it
93
What is electronegativity
The pulling power and atom has for bonded electrons
94
How is a covalent bond formed
Are you sharing a pair of electrons between two atoms
95
What is the trend in electronegativities down a group
They decrease
96
What is the trend in electronegativities across a period
They increase
97
Why do electronegativities decrease down a group
The outer electrons are further from the positive nucleus and subject to increased electron shielding due to the additional energy levels
Electrostatic forces of attraction are weaker and therefore have a weak attraction for bonding electrons i.e lower electronegativity
98
Why does electronegativity increase across period
The positive Nicola charge increases resulting in increased electrostatic force of attraction for bonded electrons I.e increased electronegativity
99
What are the three types of bonding
Metallic
Ionic
Covalent
100
What are the two types of covalent bonding
Covalent molecular
| Covalent network
101
What are the two types of covalent molecular
Intermolecular
| Intermolecular
102
What are the two types of intramolecular bonding
```
Non-polar
Polar covalent (perminent dipoles)
```
103
What are the two types of intermolecular
Dipole-dipole
| London Dispersion forces
104
Name a special type of dipole-dipole bonding
Hydrogen bonding
105
Describe ionic bonding
An electrostatic force of attraction between positive ions of metals (and some notable non metal ions like NH4*) with the negative ion of non-metals (or groups of non metals known as complex ions, for example So4^2-)
106
Explain ionic bonding
The difference in electronegativitity between metals (low) and non metals (high) results in a transfer of electrons from the metal atom to the non metal atom so creats a positive metal ion and a negative non metal ion
107
The greater the difference in electronegativity between the metal and non metals....
the greater the degree of ionic bonding
108
What is the notable exception to all metal, non metal ions being solid at room temperature
Titanium chloride (TiCL2) is a liquid and therefore not subject to ionic bonding
109
What are all ionic compounds at room temperature
Solid
110
Describe covalent bonding
Occurs between non-metal elements (there are some notable exceptions for example titanium chloride)
111
Describe non polar covalent bonds
These bonds result from non metal atoms in a molecule having the same electronegativitys
All molecules containing only non-polar covalent bonds are non polar covalent molecules
112
Why are non popular covalent molecules gases, liquids or low melting point solids at room temperature
They have properties associated with London Dispersion forces of attraction
113
Describe covalent bonds
These bonds result from non-metal atoms having different electronegativities
as a result these molecules are themselves polar
114
Are polar bond subject to London dispersion forces of attraction?
Yes
115
Describe polar molecules that are symmetrical
Molecules with polar covalent bonds but are symmetrical in shape are non-polar molecules as the polar charges cancel out
116
What can differences in electronegativities indicate
Whether an atom is Ionic, polar covalent or non polar covalent
However this is not an exact science
117
What are the three types of van de walls forces of attraction
1: London dispersion forces of attraction
2: permanent dipole forces of attraction
3: hydrogen bonding (a special version of two)
118
What are permanent dipole - permanent dipole forces of attraction
These forces of attraction results from non-metal atoms and nonsymmetrical molecules having different electronegativities for example hydrogen sulphide
There generally stronger forces of attraction when compare to London dispersion forces of attraction
119
What is hydrogen bonding
I a type of permanent dipole permanent dipole forces of attraction
These forces of attraction occur when non-metal atoms with very high electronegativities are bonded to hydrogen atoms
120
Name molecules that contain nonpolar covalent bonds
All molecular elements
(H2, N2, O2, F2, Cl2, P4, S8)
phosphine PH3
Nitrogen chloride NCl3
121
H2, N2, O2, F2, Cl2, P4, S8
phosphine PH3
Nitrogen chloride NCl3
What do all these molecules have in common
All these molecules contain nonpolar covalent bonds therefore they are nonpolar molecule subject to London dispersion forces of attraction
122
Name some symmetrical molecules
Carbon dioxide CO2
| carbon tetrachloride CCl4
123
If I symmetrical molecule contains polar bonds what kind of molecule is it
A nonpolar molecule
124
If a molecule contains non-polar bonds what kind of molecule is it
Nonpolar
125
If a molecule is not symmetrical and contains polar bonds what kind of molecule is it
Polar
126
In terms of symmetrical, polar and nonpolar molecules describe hydrocarbons
The boiling point of hydrocarbons increase with increased molecular mass and therefore increased London dispersion forces of attraction
All hydrocarbons are considered nonpolar molecules as they are all symmetrical
They are all nonpolar and therefore subject to London dispersion forces of attraction
127
What does viscosity increased with
Increasing molecular size but molecules with hydrogen bonding show higher viscosity than expected
128
What is miscibility?
Miscible liquids mix thoroughly without any visible dangers for example water and ethanol
Immiscible have a Boundry between them for example water and hexane
Hydrogen bonding helps miscibility
Other polar liquids are often miscible with water
129
What is peculiar about ice in regards to density
Normally solids are denser than their liquids but ice floats on water
130
Why does ice float on water
The intermolecular bonding associated with small covalent molecules is usually London dispersion forces of attraction.
In ice intermolecular forces of attraction is hydrogen bonding.
This results in a crystal lattice of water molecules are held together by network of hydrogen bonds
This arrangement not only makes the structure strong but it also speaks about the water molecules and so prevents them from packing closely together
131
Ionic lattices and polar covalent compounds tend to be soluble in....
Water and other polar solvents due to the interaction of opposite charges
132
Why is it that I wanna glasses and polar covalent compounds tend to be soluble in water and other polar solvents?
When I only compounds dissolved in water the lattice becomes surrounded by polar water molecules
The negative ions are attracted to the positive ends of the water molecules and the positive ions attracted to the negative end of the water molecule
133
Ions surrounded by a layer of water molecules held by electrostatic forces of attraction are said to be
Hydrated
134
Nonpolar molecules will tend to be soluble in...
Nonpolar solvents like hexane or carbon tetrachloride and insoluble in water and other polar solvents as they have no charged ends to be electrostatically attracted to the polar solvent molecules
135
Describe covalent network structures
The structures have an infinite three-dimensional network structure of non-metal atoms bonded together by covalent bonds is elements of extremely high melting and boiling points
For example silicon dioxide and silicon carbide
136
Name are used for silicon carbide
It is the hardest substance known to man and is used on abrasive wheels for cutting rocks or on grinders for sharpening metals
